1. Field of the Invention
The present invention relates to a vehicle air-conditioning apparatus, i.e., an air-conditioning apparatus for use in a vehicle.
2. Description of Related Art
There have been known technologies concerning a cooling system for a vehicle comprising a primary circulation channel and a secondary circulation channel. The secondary circulation channel circulates heat-transfer medium through a vehicle interior (i.e., indoor) air-conditioning heat-exchanger and in-vehicle devices or components (i.e., equipment set up on the vehicle) to perform air-conditioning and cool the equipment set up on the vehicle. The primary circulation channel for a refrigeration cycle system exchanges heat with the heat-transfer medium in the secondary circulation channel via an intermediate heat-exchanger provided in the secondary circulation channel. In this system, cooling of the vehicle interior and cooling of in-vehicle heat-liberation components such as batteries and DC/DC converters are performed through the primary circulation channel of the refrigerating system (see, for example, JP 2005-273998 A1).
Also, there have been known technologies concerning an air-conditioning system for vehicles comprising a primary circulation channel and a secondary circulation channel; the secondary circulation channel circulates heat-transfer medium through a heater core and the primary circulation channel serves as a heat pump (refrigeration cycle system) having an intermediate heat-exchanger provided in the secondary circulation channel in order to perform heat-exchange with the heat-transfer medium in the secondary circulation channel. In a heating mode, the heat-transfer medium in the secondary circulation channel is heated by the heat generated in the primary circulation channel of the heat pump through the intermediate heat-exchanger, and further the heat-transfer medium in the secondary circulation channel is heated by a heater, so that sufficient vehicle interior heating can be performed even when the external temperature is extremely low (see for example, JP 2008-230594 A1).